The prior art discloses various methods and apparatus for forming an expandable cellular product for window coverings and the like. U.S. Pat. Nos. 3,963,549 and 4,603,072, disclose a method of making a cellular structure from a plurality of separate tubes or separate strips that are folded into a tubular configuration, and adhered together, one on top of the other, to form longitudinally extending cells. U.S. Pat. Nos. 4,288,485 and 4,346,132 disclose a method of making a cellular structure from a plurality of sheets that are stacked and adhered together along spaced bands to form a plurality of cells between adjacent sheets. U.S. Pat. Nos. 4,631,217 and 4,677,012 disclose a method of making a cellular structure from a plurality of separate sheets that are longitudinally folded and adhered together such that each sheet forms a part of two adjacent cells. U.S. Pat. Nos. 2,201,356 and 4,625,786 disclose forming a cellular structure from two folded sheets disposed at opposite sides of a shade and connected together at spaced locations. U.S. Pat. No. to Brown 4,347,887 discloses a cellular structure formed from a single continuous sheet of material bonded to itself at spaced intervals to form a plurality of adjacent cells arranged in a double row configuration and such that the double row of cells have generally coplanar outer portions collectively forming a pair of generally parallel outer members and coplanar inner portions collectively forming a common intermediate member spaced between and generally parallel to the outer members.